U.S. patent application number 13/044363 was filed with the patent office on 2011-09-15 for fixing apparatus and image forming apparatus incorporating the same.
Invention is credited to Akifumi Isobe, Akinori KIMATA, Satoshi Shimao, Masashi Sugano, Katsunori Takahashi, Kenji Tamaki.
Application Number | 20110222922 13/044363 |
Document ID | / |
Family ID | 44560113 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110222922 |
Kind Code |
A1 |
KIMATA; Akinori ; et
al. |
September 15, 2011 |
FIXING APPARATUS AND IMAGE FORMING APPARATUS INCORPORATING THE
SAME
Abstract
Disclosed is a fixing device, which makes it possible to prevent
the air blasting section from deterioration, caused by heat
transferred from the duct to the air blasting section. The fixing
device includes a fixing section to fix the toner image onto the
paper sheet; a heat source; and a separating section to separate
the paper sheet from the pair of fixing members. On the other hand,
the separating section includes: a gas blasting section to blast a
gas; and a duct to guide the gas towards the pair of fixing
members, and that is provided with a duct wall serving as a heat
receiving surface to receive radiation heat irradiated from the
fixing section, and at least one of the gas blasting section and
the duct is provided with such a connection structure that
suppresses heat transferring action from the duct to the gas
blasting section.
Inventors: |
KIMATA; Akinori;
(Toyokawa-shi, JP) ; Sugano; Masashi; (Tokyo,
JP) ; Takahashi; Katsunori; (Tokyo, JP) ;
Isobe; Akifumi; (Hidaka-shi, JP) ; Tamaki; Kenji;
(Tokorozawa-shi, JP) ; Shimao; Satoshi; (Tokyo,
JP) |
Family ID: |
44560113 |
Appl. No.: |
13/044363 |
Filed: |
March 9, 2011 |
Current U.S.
Class: |
399/323 |
Current CPC
Class: |
B65H 29/56 20130101;
G03G 2215/2032 20130101; B65H 2801/06 20130101; B65H 2406/12
20130101; G03G 15/2028 20130101 |
Class at
Publication: |
399/323 |
International
Class: |
G03G 15/20 20060101
G03G015/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 12, 2010 |
JP |
JP2010-055980 |
Claims
1. A fixing device that is provided with a pair of fixing members,
which press-contacts with each other to form a fixing nip section,
comprising: a fixing section to apply heat and pressure onto a
toner image transferred onto a paper sheet by making the paper
sheet pass through the fixing nip section, so as to fix the toner
image onto the paper sheet; a heat source to generate the heat to
be applied onto the toner image; and a separating section to blow a
gas onto the paper sheet from a paper sheet ejection side of the
fixing nip section so as to separate the paper sheet from the pair
of fixing members; wherein the separating section comprises: a gas
blasting section to blast the gas; and a duct to guide the gas
blasted by the gas blasting section to the pair of fixing members,
and that is provided with a duct wall serving as a heat receiving
surface to receive radiation heat irradiated from the fixing
section; and wherein at least one of the gas blasting section and
the duct is provided with such a connection structure that
suppresses heat transferring action from the duct to the gas
blasting section.
2. The fixing device of claim 1, further comprising: a thermal
insulating member that is made of a material having a thermal
insulation property and that is inserted between the duct and the
gas blasting section in such a state that a flow of the gas can be
freely communicate between the duct and the gas blasting
section.
3. The fixing device of claim 1, wherein a gas blast opening of the
gas blasting section is made of a material having a thermal
insulation property, and is connected to the duct.
4. The fixing device of claim 1, wherein a gas entrance opening of
the duct is made of a material having a thermal insulation
property, and is connected to the gas blasting section.
5. The fixing device of claim 1, wherein the gas blasting section
includes a fun.
6. The fixing device of claim 1, wherein a black color coating is
applied onto an outer surface of the duct wall serving as the heat
receiving surface; and wherein the black color coating is defined
as such a coating that has any one of various kinds of colors,
having a capability for heightening a heat collecting efficiency,
as its general term.
7. The fixing device of claim 1, wherein the duct is provided with
a heat condensing fin fixed or formed onto an outer surface of the
duct wall serving as the heat receiving surface.
8. The fixing device of claim 1, wherein the duct is provided with
a heat radiation fin fixed or formed onto an inner surface of the
duct wall serving as the heat receiving surface.
9. The fixing device of claim 8, wherein the height of the heat
radiation fin is set at such a length that is shorter than a
distance between another inner surface of an opposing wall, which
opposes the inner surface of the duct wall, and the inner surface
of the duct wall, so that the heat radiation fin does not reach the
other inner surface of the opposing wall.
10. The fixing device of claim 8, wherein the heat radiation fin is
formed in such a shape that a resistance against the flow of the
gas is made to reduce.
11. The fixing device of claim 1, wherein a heat conductivity of a
material, of which an opposing wall located at an opposing side of
the duct wall is made, is lower than that of another material, of
which the duct wall serving as the heat receiving surface is
made.
12. A fixing device that is provided with a pair of fixing members,
which press-contacts with each other to form a fixing nip section,
comprising: a fixing section to apply heat and pressure onto a
toner image transferred onto a paper sheet by making the paper
sheet pass through the fixing nip section, so as to fix the toner
image onto the paper sheet; a heat source to generate the heat to
be applied onto the toner image; and a separating section to blow a
gas onto the paper sheet from a paper sheet ejection side of the
fixing nip section so as to separate the paper sheet from the pair
of fixing members; wherein the separating section comprises: a duct
to guide a flow of the gas to the pair of fixing members, and that
is provided with a duct wall serving as a heat receiving surface to
receive radiation heat irradiated from the fixing section; and
wherein the duct is provided with such a connection structure for
connecting the duct with a gas blasting section, which blasts the
flow of gas towards the duct, while suppressing heat transferring
action from the duct to the gas blasting section.
13. The fixing device of claim 12, further comprising: a thermal
insulating member that is made of a material having a thermal
insulation property; wherein the duct is structured in such a
manner that the duct is connectable with the gas blasting section
while inserting the thermal insulating member between the duct and
the gas blasting section.
14. The fixing device of claim 12, wherein a gas entrance opening
of the duct is made of a material having a thermal insulation
property, and the duct is structured in such a manner that the gas
entrance opening of the duct is connectable with the gas blasting
section.
15. The fixing device of claim 12, wherein a black color coating is
applied onto an outer surface of the duct wall serving as the heat
receiving surface; and wherein the black color coating is defined
as such a coating that has any one of various kinds of colors,
having a capability for heightening a heat collecting efficiency,
as its general term.
16. The fixing device of claim 12, wherein the duct is provided
with a heat condensing fin fixed or formed onto an outer surface of
the duct wall serving as the heat receiving surface.
17. The fixing device of claim 12, wherein the duct is provided
with a heat radiation fin fixed or formed onto an inner surface of
the duct wall serving as the heat receiving surface.
18. The fixing device of claim 17, wherein the height of the heat
radiation fin is set at such a length that is shorter than a
distance between another inner surface of an opposing wall, which
opposes the inner surface of the duct wall, and the inner surface
of the duct wall, so that the heat radiation fin does not reach the
other inner surface of the opposing wall.
19. The fixing device of claim 17, wherein the heat radiation fin
is formed in such a shape that a resistance against the flow of the
gas is made to reduce.
20. The fixing device of claim 12, wherein a heat conductivity of a
material, of which an opposing wall located at an opposing side of
the duct wall is made, is lower than that of another material, of
which the duct wall serving as the heat receiving surface is
made.
21. An image forming apparatus, comprising: a transferring unit to
transfer a toner image onto a paper sheet; and a fixing unit to fix
the toner image onto the paper sheet, onto which the toner image is
transferred by the transferring unit; wherein the fixing device is
provided with a pair of fixing members, which press-contacts with
each other to form a fixing nip section, and comprises: a fixing
section to apply heat and pressure onto the toner image transferred
onto the paper sheet by making the paper sheet pass through the
fixing nip section, so as to fix the toner image onto the paper
sheet; a heat source to generate the heat to be applied onto the
toner image; and a separating section to blow a gas onto the paper
sheet from a paper sheet ejection side of the fixing nip section so
as to separate the paper sheet from the pair of fixing members;
wherein the separating section comprises: a gas blasting section to
blast the gas; and a duct to guide the gas blasted by the gas
blasting section to the pair of fixing members, and that is
provided with a duct wall serving as a heat receiving surface to
receive radiation heat irradiated from the fixing section; and
wherein at least one of the gas blasting section and the duct is
provided with such a connection structure that suppresses heat
transferring action from the duct to the gas blasting section.
Description
[0001] This application is based on Japanese Patent Application NO.
2010-055980 filed on Mar. 12, 2010, with Japan Patent Office, the
entire content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a fixing device and an
image forming apparatus.
[0003] Conventionally, there have been well known various kinds of
image forming apparatuses that employ the electro-photographic
method, such as a printer, a copier, etc. In the image forming
apparatus categorized in the abovementioned kind, the operation for
fixing a toner image, formed on a paper sheet, onto the paper sheet
concerned has been achieved by making the paper sheet Pass through
a press-contact section (hereinafter, referred to as a fixing nip
area) formed between a pair of fixing members (such as, a pair of
fixing rollers), which constitute the fixing device, so as to apply
heat and pressure onto the paper sheet concerned. Since the heat
and pressure are employed for the fixing operation, sometimes,
there has occurred such a trouble that the fixing member has been
rolled in the paper sheet that passed through the fixing nip area
without separating from the fixing member.
[0004] For instance, Tokkai 2005-157179 (Japanese Patent
Application Laid-Open Publication) sets forth such the image
forming apparatus that is provided with the separation section for
making the paper sheet separate from the fixing member. Concretely
speaking, the separation section is constituted by the compressor
(air-pump) serving as an air blasting device, and the nozzle, the
air blasting edge portion of which is disposed at the paper sheet
ejection side of the fixing nip area, so that the pulses of the
compression air are emitted from the compressor through the nozzle
so as to make the paper sheet separate from the fixing member.
Further, Tokkai 2005-157179 also sets forth such the method in
which the nozzle is disposed near the circumferential surface of
the fixing member, so as to heat up the temperature of the
compression air by utilizing the radiation heat irradiated from the
fixing member or the heat generated by the heating device
incorporated independently, and then, the heated compression air is
emitted.
[0005] According to the method set fort in Tokkai 2005-157179,
however, there has been such a fear that, since the heat to be
employed for heating up the compression air is also transferred to
the air blasting device concerned, the separation section would be
deteriorated considerably.
SUMMARY OF THE INVENTION
[0006] To overcome the abovementioned drawbacks in conventional
image forming apparatus, it is one of objects of the present
invention to provide a fixing device and an image forming apparatus
employing the same, which makes it possible to stably operate the
separating section and to extend its lifetime, by suppressing the
deterioration caused by heat.
[0007] Accordingly, at least one of the objects of the present
invention can be attained by any one of the fixing devices and the
image forming apparatus described as follows.
(1) According to a fixing device reflecting an aspect of the
present invention, the fixing device that is provided with a pair
of fixing members, which press-contacts with each other to form a
fixing nip section, comprises: a fixing section to apply heat and
pressure onto a toner image transferred onto a paper sheet by
making the paper sheet pass through the fixing nip section, so as
to fix the toner image onto the paper sheet; a heat source to
generate the heat to be applied onto the toner image; and a
separating section to blow a gas onto the paper sheet from a paper
sheet ejection side of the fixing nip section so as to separate the
paper sheet from the pair of fixing members; wherein the separating
section comprises: a gas blasting section to blast the gas; and a
duct to guide the gas blasted by the gas blasting section to the
pair of fixing members, and that is provided with a duct wall
serving as a heat receiving surface to receive radiation heat
irradiated from the fixing section; and wherein at least one of the
gas blasting section and the duct is provided with such a
connection structure that suppresses heat transferring action from
the duct to the gas blasting section. (2) According to another
aspect of the present invention, the fixing device recited in item
1, further comprises: a thermal insulating member that is made of a
material having a thermal insulation property and that is inserted
between the duct and the gas blasting section in such a state that
a flow of the gas can be freely communicate between the duct and
the gas blasting section. (3) According to still another aspect of
the present invention, in the fixing device recited in item 1, a
gas blast opening of the gas blasting section is made of a material
having a thermal insulation property, and is connected to the duct.
(4) According to still another aspect of the present invention, in
the fixing device recited in item 1, a gas entrance opening of the
duct is made of a material having a thermal insulation property,
and is connected to the gas blasting section. (5) According to
still another aspect of the present invention, in the fixing device
recited in any one of items 1-4, the gas blasting section includes
a fun. (6) According to still another aspect of the present
invention, in the fixing device recited in any one of items 1-5, a
black color coating is applied onto an outer surface of the duct
wall serving as the heat receiving surface, and the black color
coating is defined as such a coating that has any one of various
kinds of colors, having a capability for heightening a heat
collecting efficiency, as its general term. (7) According to still
another aspect of the present invention, in the fixing device
recited in any one of items 1-6, the duct is provided with a heat
condensing fin fixed or formed onto an outer surface of the duct
wall serving as the heat receiving surface. (8) According to still
another aspect of the present invention, in the fixing device
recited in any one of items 1-7, the duct is provided with a heat
radiation fin fixed or formed onto an inner surface of the duct
wall serving as the heat receiving surface. (9) According to still
another aspect of the present invention, in the fixing device
recited in item 8, the height of the heat radiation fin is set at
such a length that is shorter than a distance between another inner
surface of an opposing wall, which opposes the inner surface of the
duct wall, and the inner surface of the duct wall, so that the heat
radiation fin does not reach the other inner surface of the
opposing wall. (10) According to still another aspect of the
present invention, in the fixing device recited in item 8 or 9, the
heat radiation fin is formed in such a shape that a resistance
against the flow of the gas is made to reduce. (11) According to
still another aspect of the present invention, in the fixing device
recited in any one of items 1-10, a heat conductivity of a
material, of which an opposing wall located at an opposing side of
the duct wall is made, is lower than that of another material, of
which the duct wall serving as the heat receiving surface is made.
(12) According to an image forming apparatus reflecting yet another
aspect of the present invention, the image forming apparatus,
comprises: a transferring unit to transfer a toner image onto a
paper sheet; and a fixing unit to fix the toner image onto the
paper sheet, onto which the toner image is transferred by the
transferring unit; wherein the fixing device is provided with a
pair of fixing members, which press-contacts with each other to
form a fixing nip section, and comprises: a fixing section to apply
heat and pressure onto the toner image transferred onto the paper
sheet by making the paper sheet pass through the fixing nip
section, so as to fix the toner image onto the paper sheet; a heat
source to generate the heat to be applied onto the toner image; and
a separating section to blow a gas onto the paper sheet from a
paper sheet ejection side of the fixing nip section so as to
separate the paper sheet from the pair of fixing members; wherein
the separating section comprises: a gas blasting section to blast
the gas; and a duct to guide the gas blasted by the gas blasting
section to the pair of fixing members, and that is provided with a
duct wall serving as a heat receiving surface to receive radiation
heat irradiated from the fixing section; and wherein at least one
of the gas blasting section and the duct is provided with such a
connection structure that suppresses heat transferring action from
the duct to the gas blasting section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Embodiments will now be described, by way of example only,
with reference to the accompanying drawings which are meant to be
exemplary, not limiting, and wherein like elements are numbered
alike in several Figures, in which:
[0009] FIG. 1 shows an explanatory schematic diagram indicating a
configuration of an image forming apparatus embodied in the present
invention;
[0010] FIG. 2 shows a cross sectional schematic diagram indicating
an exemplified structure of a fixing device embodied in the present
invention;
[0011] FIG. 3 shows a perspective view indicating three air
blasting funs and three thermal insulating members, which
constitute three separating sections, respectively;
[0012] FIG. 4 shows a perspective view indicating a fixing device
in such a state that three air blasting funs and three thermal
insulating members are removed therefrom;
[0013] FIG. 5 shows a perspective view indicating a duct
schematically;
[0014] FIG. 6 shows an explanatory schematic diagram indicating a
modified connection structure between a duct and an air blasting
fun;
[0015] FIG. 7 shows an explanatory schematic diagram indicating
another modified connection structure between a duct and an air
blasting fun;
[0016] FIG. 8 shows a perspective view schematically indicating a
duct constituting a separating section of a fixing device, embodied
in the present invention as the second embodiment;
[0017] FIG. 9 shows a perspective view schematically indicating a
duct constituting a separating section of a fixing device, embodied
in the present invention as the third embodiment; and
[0018] FIG. 10 shows a perspective view schematically indicating a
duct constituting a separating section of a fixing device, embodied
in the present invention as the fourth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
First Embodiment
[0019] FIG. 1 shows an explanatory schematic diagram indicating a
configuration of an image forming apparatus 1 embodied in the
present invention. For instance, the image forming apparatus 1
serves as such an image forming apparatus that employs the
electro-photographic image forming method, such as a copier or the
like, and is configured as, so called, a tandem-type color image
forming apparatus in which a plurality of photoreceptor members
(photoreceptor drums) are arranged in a vertical direction in such
a manner that the plurality of photoreceptor members opposes to a
single intermediate transfer belt so as to form a full color image
onto a sheet.
[0020] The image forming apparatus 1 is constituted by a document
reading section 10, exposure sections 20Y, 20M, 20C and 20K, image
forming sections 30Y, 30M, 30C and 30K, an intermediate transfer
section 40, a fixing device 50, a paper sheet ejecting and
reversing section 70, a paper sheet re-feeding section 80 and a
paper sheet feeding section 90, as its main constituents, which are
accommodated into a single housing.
[0021] The document reading section 10 is provided with an
automatic document feeder ADF mounted thereon. Documents D placed
on a document placing plate 15 of the automatic document feeder ADF
are sequentially picked up one by one and conveyed onto a document
conveyance path, and further conveyed by a conveyance drum 16. A
first conveyance guide G1 and a pair of document ejection rollers
17 guide and eject each of the documents D, conveyed by the
conveyance drum 16, onto a document ejection tray 18.
[0022] The document reading section 10 reads an image of each of
the documents Data document image reading position RP, while the
conveyance drum 16 is conveying the concerned document D.
Concretely speaking, a lamp L irradiates light onto the image of
the concerned document D at the document image reading position RP.
Then, a first mirror unit 11, a second mirror unit 12 and a lens
unit 13 guide reflection light reflected from the concerned image
to a light receiving surface of an imager CCD (Charge Coupled
Device), so as to focus the reflection light onto the light
receiving surface of the imager CCD. The imager CCD converts the
incident light to analogue image signals through the process of the
photoelectric converting actions, and outputs the image signals in
the predetermined format. An image reading control section 14
applies various kinds of image processing, such as an analogue to
digital conversion processing, a shading correction processing, a
compression processing, etc., to the image signals outputted by the
imager CCD, and stores the processed image data, acquired as a
result of applying the abovementioned image processing, into a
storage section provided in a control section (not shown in the
drawings) as inputted image data. Successively, according to the
condition established by the user, an appropriate image processing
is further applied to the inputted image data stored in the storage
section, so as to generate output image data. In this connection,
the scope of the inputted image data is not limited to those
acquired from the image signals read by the document reading
section 10. For instance, image data received from a personal
computer or another image forming apparatus, which are coupled to
the image forming apparatus 1, may also serve as the inputted image
data above-mentioned.
[0023] Each of the exposure sections 20Y, 20M, 20C and 20K is
constituted by a laser light source (not shown in the drawings), a
polygon mirror, a plurality of lenses, etc., so as to emit a laser
beam therefrom. Each of the exposure sections 20Y, 20M, 20C and 20K
emits the laser beam, the intensity of which is modulated in
response to the output information outputted by the control section
based on the output image data, so as to perform the scanning
exposure operation by scanning the laser beam onto the
circumferential surface of corresponding one of photoreceptor drums
31Y, 31M, 31C and 31K, serving as constituents of the image forming
sections 30Y, 30M, 30C and 30K, respectively. As a result of the
scanning exposure operation employing the laser beam, latent images
are formed on the circumferential surfaces of the photoreceptor
drums 31Y, 31M, 31C and 31K.
[0024] The image forming section 30Y is constituted by the
photoreceptor drum 31Y, and a main charging section 32Y, a
developing section 33Y, a first transferring roller 34Y and a
cleaning section 35Y, which are arranged along the circumferential
surface of the photoreceptor drum 31Y within the peripheral space
thereof. Each of the configurations of the other image forming
sections 30M, 30C and 30K are substantially the same as that of the
image forming section 30Y above-mentioned. Namely, the other image
forming sections 30M, 30C and 30K are respectively constituted by
photoreceptor drums 31M, 31C, 31K, and main charging sections 32M,
32C, 32K, developing sections 33M, 33C, 33K, first transferring
rollers 34M, 34C, 34K and cleaning sections 35M, 35C, 35K, which
are respectively arranged along the circumferential surfaces of the
photoreceptor drum 31M, 31C, 31K within the peripheral spaces
thereof.
[0025] The main charging sections 32Y, 32M, 32C and 32K uniformly
charge the circumferential surfaces of the photoreceptor drums 31Y,
31M, 31C and 31K, respectively, so as to make it possible to form
latent images thereon. Then, the developing section 33Y, 33M, 33C
and 33K develop the latent images formed on the circumferential
surfaces of the photoreceptor drums 31Y, 31M, 31C and 31K, with
toner, to yield visual images thereon, respectively. According to
the abovementioned process, visual toner images are formed on the
circumferential surfaces of the photoreceptor drums 31Y, 31M, 31C
and 31K, respectively.
[0026] The toner images, respectively formed on the photoreceptor
drums 31Y, 31M, 31C and 31K, are sequentially transferred onto a
predetermined area of an intermediate transfer belt 41, threaded on
the intermediate transfer section 40, one by one, under the
transferring actions performed by the first transferring rollers
34Y, 34M, 34C and 34K respectively. Successively, the cleaning
sections 35Y, 35M, 35C and 35K remove residual toner remaining on
the photoreceptor drums 31Y, 31M, 31C and 31K after the toner image
transferring operations have been completed, respectively.
[0027] The full color toner image formed on the intermediate
transfer belt 41 through the abovementioned process is further
transferred onto a paper sheet P under the transferring action
performed by a second transferring roller 42. The paper sheet P to
be employed for the transferring operation is fed from any one of
paper sheet accommodating trays PG1, PG2 and PG3 included in the
paper sheet feeding section 90, and then, conveyed to the position
of the second transferring roller 42 while a paper sheet feeding
roller 91 adjusts the timing for feeding the paper sheet P thereto.
After the current operation for transferring the full color toner
image has been completed, a belt cleaning section 43 cleans the
surface of the intermediate transfer belt 41 so as to prepare the
intermediate transfer belt 41 for a next image transferring
operation.
[0028] The paper sheet P, bearing the full color toner image
thereon, is conveyed to the fixing device 50, in which the full
color toner image is fixed onto the paper sheet P by applying heat
and pressure onto the paper sheet P. In this connection, the
details of the fixing device 50 will be described later on.
[0029] The paper sheet ejecting and reversing section 70 conveys
the paper sheet P, for which the fixing operation has been
completed by the fixing device 50, and ejects the paper sheet P
concerned onto a paper sheet ejection tray 75. When the paper sheet
P is ejected in the obverse and reverse sides inversion mode, an
ejection guide 72 once guides the paper sheet P downward. Then,
after a pair of ejection reversing rollers 73 has tightly clipped
the trailing edge portion of the paper sheet P, the pair of
ejection reversing rollers 73 conveys the paper sheet P concerned
in the reverse direction, and then, the ejection guide 72 guides
the paper sheet P to a pair of ejection rollers 74, so that the
pair of ejection rollers 74 ejects the paper sheet P onto the paper
sheet ejection tray 75.
[0030] In this connection, in the case of the duplex image forming
mode in which the image forming operation is also applied to the
reverse side of the paper sheet P, the ejection guide 72 conveys
the paper sheet P, onto obverse side of which the operation for
fixing the full color toner image has been completed, to the paper
sheet re-feeding section 80 disposed at a downward position. After
a pair of re-feed reversing rollers 81 has tightly clipped the
trailing edge portion of the paper sheet P, the pair of re-feed
reversing rollers 81 conveys the paper sheet P concerned in the
reverse direction, so as to convey the paper sheet P, the obverse
and reverse sides of which are inverted each other, to a paper
sheet re-feeding path 82. According to the abovementioned process,
the image forming operation is also applied to the reverse side of
the paper sheet P.
[0031] The fixing device 50 is constituted by a fixing section 51
and a separating section 56. Incidentally, FIG. 2 shows a cross
sectional schematic diagram indicating an exemplified structure of
the fixing device 50 embodied in the present invention.
[0032] The fixing section 51 is constituted by a heating roller 52,
a fixing roller 53, an endless type fixing belt 54 and a pressure
roller 55, as its constituents. The heating roller 52 and the
fixing roller 53 are disposed in such a manner that both of them
are apart from each other so as to place a predetermined distance
between them. Further, the endless type fixing belt 54 is threaded
on the heating roller 52 and the fixing roller 53. The pressure
roller 55 is disposed in such a manner that the pressure roller 55
press-contacts the endless type fixing belt 54 within an area in
which the endless type fixing belt 54 and the fixing roller 53
contact with each other, so as to form a fixing nip section NP at
the press-contacted area formed between the endless type fixing
belt 54 and the pressure roller 55.
[0033] In the fixing device 50, the paper sheet P is conveyed in
such a manner that the fixing objective surface (namely, the
surface, which currently bears the non-fixed toner image) opposes
to the endless type fixing belt 54, and passes through the fixing
nip section NP during the process of conveying the paper sheet P.
Trough the abovementioned process, the operation for fixing the
full color toner image onto the paper sheet P is achieved by
applying both the heat, conducted from the endless type fixing belt
54 (fixing roller 53), and the pressure, generated by the pressure
roller 55, to the paper sheet P concerned. Then, a pair of ejecting
rollers 60 ejects the paper sheet P, on which the full color toner
image has been fixed, outside the fixing device 50.
[0034] The heating roller 52, for instance, is structured by
laminating a coating layer (for instance, a fluorine resin) onto a
circumferential surface of a pipe made of a cylinder-shaped steel
or aluminum, so as to prevent the circumferential surface of the
pipe from wearing due to the abrasion with the endless type fixing
belt 54. In the interior of the heating roller 52, a heater 52a for
heating the endless type fixing belt 54, which serves as a heat
generating source for thermo-fixing a toner image residing on the
paper sheet P, is incorporated. The heating roller 52 is heated by
the radiation heat generated by the heater 52a, and then, the heat
stored in the heating roller 52 is transmitted to the endless type
fixing belt 54. The heating roller 52 is driven to rotate by a
driving force transmitted from a driving member (not shown in the
drawings, for instance, a motor), so as to drive the endless type
fixing belt 54 to circulate around the fixing roller 53 in
accordance with the rotating action of the heating roller 52.
[0035] The fixing roller 53 is structured by laminating an elastic
layer made of an elastic material, such as a silicone rubber, a
sponge, etc., onto a circumferential surface of a column-shaped
steel or aluminum. Incidentally, the present embodiment is so
constituted that the fixing roller 53 is indirectly heated by the
heat generated by the heater 52a.
[0036] The endless type fixing belt 54 serves as an endless belt
structured by laminating a heat resistance layer, an elastic layer
and a coating layer, and having a flexibility. In the present
embodiment, the heating roller 52 is directly heated by the heater
52a, and then, the heat stored in the heating roller 52 is
transferred (thermo-conducted) to the endless type fixing belt 54,
so as to heat the endless type fixing belt 54 up to the fixing
temperature.
[0037] The pressure roller 55 is structured by laminating an
elastic layer made of a silicone rubber or the like, a separation
layer made of a fluorine resin or the like, etc., onto a
circumferential surface of a pipe made of a cylinder-shaped steel
or aluminum. In this connection, the pressure roller 55 also
incorporates a heater in the interior thereof so as to make it
possible to apply supplemental heat for achieving the thermo-fixing
operation to the paper sheet P.
[0038] The separating section 56 is constituted by an air blasting
fun 57, a duct 58 and a thermal insulating member 59. The air
blasting fun 57 and the duct 58 are connected to each other, while
inserting the thermal insulating member 59 between them in such a
manner that the air can be communicated through the thermal
insulating member 59 so as not to impede the air flow from the air
blasting fun 57 to the duct 58.
[0039] The separating section 56 is disposed downstream the fixing
section 51 in a conveyance path FP of paper sheet P so that the
leading edge portion (an air blow opening 58c, detailed later) of
the duct 58 is arranged at a position opposing the paper sheet
ejection side of the fixing nip section NP. The air blasted by the
air blasting fun 57 flows through the interior of the duct 58, and
then, is emitted from an air blow opening 58c, so as to separate
the paper sheet P from the endless type fixing belt 54 by employing
the air pressure of the airflow (separation wind) blown from the
air blow opening 58c. In the present embodiment, three separating
sections 56, each being equivalent to the above-mentioned
separating section 56, are arranged horizontally in a paper sheet
width direction (orthogonal to the paper sheet conveyance
direction).
[0040] FIG. 3 shows a perspective view indicating the three air
blasting funs 57 and the three thermal insulating members 59, which
constitute the three separating sections 56, respectively, while
FIG. 4 shows a perspective view indicating the fixing device 50 in
such a state that the three air blasting funs 57 and the three
thermal insulating members 59 are removed therefrom. The air
blasting fun 57 takes the air into the interior thereof from an air
intake opening 57a, so as to blast the air through an air blast
opening 57b. The three air blasting funs 57 are mounted onto an
outer wall surface (an upper wall surface 50a, in the present
embodiment) of the housing in which the fixing section 51 and a
part of the separating section 56 (duct 58) are accommodated.
Concretely speaking, the three thermal insulating members 59,
detailed later, are attached onto the three air intake openings
57a, respectively, and then, the three air blasting funs 57 are
mounted onto the upper wall surface 50a in such a manner that the
three air intake openings 57a correspond to three opening sections
50b provided on the upper wall surface 50a, respectively. Due to
the fact that the air blasting fun 57 takes the air into the
interior thereof, the disposition of the three air blasting funs 57
are determined by considering various kinds of design demands
(design factors), such as the fact that it is convenient to dispose
the air blasting fun 57 outside the housing, a demand for
shortening the distance from the air blasting fun 57 to the endless
type fixing belt 54 (traveling distance of the separation wind) as
shorter as possible, a demand for disposing the duct 58 at a
position near the heating roller 52 (heater 52a), etc. In this
connection, the scope of the shape and configuration of the air
blasting fun 57 is not limited to those abovementioned. Any kind of
shape and configuration is applicable in the present invention, as
far as the concerned fan satisfies the function for blasting the
air. Further, it is also applicable that the air blasting fun 57
blasts the air residing inside the machine instead of the air
residing outside the machine. Still further, it is also applicable
that the air blasting fun 57 blasts a certain kind of gas other
than the air.
[0041] FIG. 5 shows a perspective view indicating the duct 58
schematically. The duct 58 is made of a metal material, such as an
aluminum, etc., the cross sectional shape of which is formed in a
rectangular, and is disposed at a position near the heating roller
52 (heater 52a). When the duct 58 is apprehended from the
functional point of view, the duct 58 is constituted by an air
entrance opening 58a from which the air is blasted into the duct
58, an airflow guide section 58b guiding the airflow concerned, and
the air blow opening 58c from which the air is brown. The air
blasted from the air entrance opening 58a is guided along the
airflow guide section 58b, and is ejected from the air blow opening
58c.
[0042] The air entrance opening 58a is formed in such a shape that
corresponds to the shape of the air blast opening 57b, so that the
air entrance opening 58a is attached to the opening section 50b
provided on the upper wall surface 50a of the housing. The air blow
opening 58c is disposed at such a position that is shifted towards
the endless type fixing belt 54 side from the front position
located at the ejection side of the fixing nip section NP (above
the conveyance path FP of the paper sheet P), and that the air is
brown to the heating roller 52 along a tangential direction of the
endless type fixing belt 54. The abovementioned disposition of the
air blow opening 58c is determined on the basis of the knowledge
acquired by the present inventors, such that, among the endless
type fixing belt 54 and the pressure roller 55, both of which
contact the paper sheet P at fixing nip section NP, the tendency
(possibility) that the paper sheet P wraps around the endless type
fixing belt 54, which substantially contacts the fixing objective
surface of the paper sheet P, is stronger than that of the other.
In addition to the abovementioned, the shape of the air blow
opening 58c is formed in such an opening shape that is elongated in
a longitudinal direction coinciding with the width direction of the
paper sheet P (direction orthogonal to the conveyance direction of
the paper sheet P). Due to the elongated opening shape
abovementioned, it becomes possible not only to make the separation
wind widely spread in the width direction of the paper sheet P, but
also to suppress the unevenness of the wind amount distribution in
the width direction of the paper sheet P.
[0043] In the duct 58, a black color coating BP is applied onto a
surface of the duct wall constituting the airflow guide section
58b, namely, an outer surface of a duct wall that opposes to the
heating roller 52 (hereinafter, referred to as an opposing wall
surface 58d). Since the air entrance opening 58a opposes to the
heating roller 52, the air entrance opening 58a serves as a heat
receiving surface for receiving the radiation heat irradiated from
the heating miler 52 (radiation heat caused by the heater 52a).
Further, by applying the black color coating BP onto the outer
surface of the opposing wall surface 58d, it becomes possible to
heighten the efficiency for absorbing the radiation heat irradiated
from the heating roller 52, as an innovation to be applied.
Receiving the radiation heat irradiated from the heating roller 52
onto the heat receiving surface (opposing wall surface 58d), the
duct 58 transfers the above-absorbed heat to the air (separation
air) currently flowing inside the airflow guide section 58b, so as
to heat up the separation air.
[0044] The thermal insulating member 59 is formed in shape of
rectangular frame having a through hole area corresponding to the
air entrance opening 58a of the duct 58, therein, and is made of a
material that suppresses the thermal conduction, in other words,
made of a material having thermal insulation properties. The
thermal insulating member 59 is inserted between the duct 58 and
the air blasting fun 57, so that both of them are connected in such
a state that the airflow can be freely communicate between
them.
[0045] As described in the foregoing, according to the present
embodiment, the opposing wall surface 58d of the duct 58 serves as
the heat receiving surface that receives the radiation heat
irradiated from the fixing section 51. Further, the structure of
the duct 58 and the air blasting fun 57 is provided with the
thermal insulating member 59, serving as the connection structure
that suppresses the thermal conduction from duct 58 to the air
blasting fun 57, therebetween. Among the parts constituting the air
blasting fun 57, some kinds of parts, such as a bearing that
rotatably support the propeller shaft, electronic parts including
capacitors mounted into the driving circuit, etc., are
substantially vulnerable in the high temperature environment, and
therefore, are factors for causing the deterioration of the air
blasting fun 57. According to the present embodiment, however, even
when the temperature of the duct 58 has risen due to the influence
of the heat receiving surface, it becomes possible to prevent the
air blasting fun 57 form causing such inconvenience that the heat
of the duct 58 is transferred to the air blasting fun 57 to
excessively rise the temperature thereof.
[0046] Further, according to the present embodiment, the air can be
heated up by the radiation heat received by the heat receiving
surface during the process that the air, blasted by the air
blasting fun 57, is flowing through the inside of the duct 58.
Accordingly, it becomes possible to prevent the fixing device 50
from causing such an inconvenient situation that the fixing
temperature is excessively lowered by blowing a low temperature
separation wind to the fixing nip section NP. Further, compared to
such the conventional case that intermittent air blows are emitted,
since a constant amount of air can be continuously blasted by
employing the air blasting fun 57, it becomes possible to conduct
the air blasting operation in a stable state. Accordingly, it
becomes possible to prevent the fixing device 50 from causing such
an inconvenient state that the fixing temperature becomes
unstable.
[0047] Still further, according to the present embodiment, the air
blasting fun 57 is disposed at a position located in the peripheral
space of the fixing device 50 (upper wall surface 50a). Since the
compression ratio of the air blasting fun 57 is relatively small,
compared to that of a compressor or the like, there has been such a
possibility that the longer the traveling path of the separation
wind is, the more insufficient the wind velocity to be acquired at
the time of the operation for separating the paper sheet P becomes.
According to the present embodiment, however, by employing the
above-mentioned disposition of the air blasting fun 57, it becomes
possible to shorten the distance from the air blasting fun 57 to
the endless type fixing belt 54 (length of the traveling path of
the separation wind). Incidentally, although the air blasting fun
57 is exemplified as the air blasting device for blasting the
separation wind in the present embodiment, other than the above, it
is also applicable that, for instance, a blower is employed as the
air blasting device for continuously blasting the separation
wind.
[0048] In this connection, according to the connecting structure
between the duct 58 and the air blasting fun 57 in the present
embodiment, the thermal insulating member 59 is inserted between
the duct 58 and the air blasting fun 57, so as to suppress the heat
transferring action from the duct 58 to the air blasting fun 57.
However, the scope of the connecting structure between the duct 58
and the air blasting fun 57 is not limited to the above. The
following method can be also employed, as far as the connecting
structure between the duct 58 and the air blasting fun 57 is such a
structure that the heat transferring action from the duct 58 to the
air blasting fun 57 can be suppressed.
[0049] As shown in FIG. 6, it is applicable that, in the air
blasting fun 57, the length of the air blast opening 57b (indicated
by the hatched area shown in FIG. 6) is set at a predetermined
value in the air blasting direction, and the air blast opening 57b
is made of such a material that has a heat insulation property (for
instance, an urethane foam). According to the connecting structure
shown in FIG. 6, the air blasting fun 57 and the duct 58 are
connected to each other in such a manner that the air blast opening
57b is directly connected to the air entrance opening 58a of the
duct 58. Even if the abovementioned connecting structure is
employed, the air blast opening 57b of the air blasting fun 57
surely serves as the member for suppressing the heat transferring
action from the duct 58 to the air blasting fun 57. Accordingly, it
becomes possible to prevent the fixing device 50 from causing such
an inconvenient situation that the heat is transferred from the
duct 58, heated by the heating roller 52, to the main body of the
air blasting fun 57, without employing the thermal insulating
member 59.
[0050] Further, as shown in FIG. 7, in the duct 58, the length of
the air entrance opening 58a (indicated by the hatched area shown
in FIG. 7) is set at a predetermined value in the air blasting
direction, and the air entrance opening 58a is made of such a
material that has a heat insulation property (for instance, an
urethane foam). According to the connecting structure shown in FIG.
7, the air blasting fin 57 and the duct 58 are connected to each
other in such a manner that the air entrance opening 58a is
directly connected to the air blast opening 57b of the air blasting
fun 57. Even if the above-mentioned connecting structure is
employed, the air entrance opening 58a of the duct 58 surely serves
as the member for suppressing the heat transferring action from the
duct 58 to the air blasting fun 57. Accordingly, it becomes
possible to prevent the fixing device 50 from causing such an
inconvenient situation that the heat is transferred from the duct
58, heated by the heating roller 52, to the main body of the air
blasting fun 57, without employing the thermal insulating member
59.
[0051] Still further, it is also applicable that the combination of
the thermal insulating member 59, indicated in the aforementioned
embodiment, and any one or both of the methods, shown in FIGS. 6
and 7, is employed as the connecting structure between the air
blasting fun 57 and the duct 58. According to the abovementioned
combination, it becomes possible to suppress the heat transferring
action between the air blasting fun 57 and the duct 58 more
effectively than ever.
[0052] In the embodiment exemplified in the above, the black color
coating BP is applied onto the opposing wall surface 58d, serving
as the heat receiving surface, so as to heighten the heat
collecting efficiency thereof. However, the scope of the color of
the coating is not limited to the black color. Any one of various
kinds of colors may be applicable as the color of the coating, as
far as the heat collecting efficiency can be heightened by applying
the coating BP of the color concerned. Hereinafter in the present
specification, the coating, having any one of various kinds of
colors that have a capability for heightening the heat collecting
efficiency, is defined as the black color coating BP as its general
term.
[0053] Further, although the outer wall surface of the duct 58,
opposing to the fixing section 51, (opposing wall surface 58d) is
employed as the heat receiving surface in the present embodiment,
the scope of the heat receiving surface is not limited to the
above. Any surface may be employed as the heat receiving surface,
as far as the concerned surface can receive the radiation heat
irradiated from the fixing section 51.
Second Embodiment
[0054] FIG. 8 shows a perspective view schematically indicating the
duct 58 constituting the separating section 56 of the fixing device
50, embodied in the present invention as the second embodiment. The
point that the duct 58 of the second embodiment is different from
that of the first embodiment is the structure of the opposing wall
surface 58d for receiving the radiation heat irradiated from the
heating roller 52. In this connection, the different points between
the first and second embodiments will be mainly detailed in the
following, while the duplicate descriptions same as those of the
first embodiment will be omitted.
[0055] In the structure of the second embodiment, the duct 58 is
provided with a plurality of heat condensing fins 58f formed on the
outer surface of the opposing wall surface 58d. Each of the
plurality of heat condensing fins 58f is formed by employing a
plate shaped member elongated in the wind blasting direction, and
the plural heat condensing fins 58f are arranged in the width
direction (direction orthogonal to the wind blasting direction
among the two dimensional directions on the opposing wall surface
58d) at equal intervals. For instance, each of the plurality of
heat condensing fins 58f is made of a metal material having high
heat conductivity, such as an aluminum, etc., and is welded onto
the outer surface of the opposing wall surface 58d.
[0056] According to the second embodiment as described in the
above, it becomes possible to make the duct 58 secure the total
heat receiving area being wider than ever, compared to such the
case that the opposing wall surface 58d, serving as the heat
condensing surface, is formed in the flat surface shape.
Accordingly, it becomes possible to efficiently collect the
radiation heat irradiated from the heating roller 52, so as to make
it possible to effectively heat the air flowing through the
interior of the duct 58.
[0057] In this connection, although each of plurality of heat
condensing fins 58f is structured to elongate in the wind blasting
direction in the second embodiment, the structural scope of the
plurality of heat condensing fins 58f is not limited to the above.
It is also applicable that, for instance, each of plurality of heat
condensing fins 58f is structured to elongate in the width
direction, or in any other direction. Further, although the plate
shaped member is straightly elongated to form each of plurality of
heat condensing fins 58f in the second embodiment, it is also
applicable that the plate shaped member is elongated along any one
of various kinds of curved lines, such as a waveform curvature, a
sawtooth curvature, etc., to form each of plurality of heat
condensing fins 58f. Still further, although each of plurality of
heat condensing fins 58f is formed as the plate shaped member in
the second embodiment, it is also applicable that each of plurality
of heat condensing fins 58f is formed as a column shaped
member.
Third Embodiment
[0058] FIG. 9 shows a perspective view schematically indicating the
duct 58 constituting the separating section 56 of the fixing device
50, embodied in the present invention as the third embodiment. The
point that the duct 58 of the third embodiment is different from
that of the first embodiment is the structure for transferring the
heat received by the opposing wall surface 58d, serving as the heat
receiving surface that receives the radiation heat irradiated from
the heating roller 52, to the separation wind. In this connection,
the different points between the first and third embodiments will
be mainly detailed in the following, while the duplicate
descriptions same as those of the first embodiment will be
omitted.
[0059] In the structure of the third embodiment, the duct 58 is
provided with a plurality of heat radiation fins 58g formed on the
inner surface of the opposing wall surface 58d. Each of the
plurality of heat radiation fins 58g is formed by employing a plate
shaped member elongated in the wind blasting direction, and the
plural heat radiation fins 58g are arranged in the width direction
(direction orthogonal to the wind blasting direction among the two
dimensional directions on the opposing wall surface 58d) at equal
intervals. For instance, each of the plurality of heat radiation
fins 58g is made of a metal material having high heat conductivity,
such as an aluminum, etc., and is welded onto the outer surface of
the opposing wall surface 58d. Further, the height of each of the
plurality of heat radiation fins 58g is set at such a length that
is shorter than the distance between the opposing wall surface 58d
and a duct wall 58e, which opposes the opposing wall surface 58d,
in its height direction (direction perpendicular to the opposing
wall surface 58d), so as not to reach the inner surface of the duct
wall 58e.
[0060] According to the third embodiment as described in the above,
since it is possible to heighten the heat transfer efficiency from
the plurality of heat radiation fins 58g provided on the opposing
wall surface 58d to the separation wind, it becomes possible to
effectively heat up the separation wind. Further, the height of
each of the plurality of heat radiation fins 58g is set at such the
length that is shorter than the distance between the opposing wall
surface 58d and a duct wall 58e, so as not to make the top portions
of the heat radiation fins 58g contact the inner surface of the
duct wall 58e. If any one of the top portions of the heat radiation
fins were in contact with the inner surface of the duct wall 58e,
the heat would be dispersed outside the duct 58 through the duct
wall 58e, possibly resulting in the deterioration of the heating
efficiency of the separation wind. According to the third
embodiment, however, by restricting the height of each of the
plurality of heat radiation fins 58g, it becomes possible to
suppress such the inconvenience as above-mentioned.
[0061] In this connection, the third embodiment is so constituted
that each of the plurality of heat radiation fins 58g is elongated
in the wind blasting direction. This is an innovation for
alleviating the air resistance to be generated between the
separation wind and the plurality of heat radiation fins 58g, and
the present inventors have derived this innovation from such a
viewpoint that the plurality of heat radiation fins 58g should be
equipped so as not to impede the airflow of the separation wind.
However, if the air resistance is not such the main factor for
impeding the airflow, it is possible to employ any one of various
kinds of structures as described in the second embodiment.
[0062] Further, it is needless to say that the third embodiment
including the plurality of heat radiation fins 58g is combinable
with the second embodiment including the plurality of heat
condensing fins 58f.
Fourth Embodiment
[0063] FIG. 10 shows a perspective view schematically indicating
the duct 58 constituting the separating section 56 of the fixing
device 50, embodied in the present invention as the fourth
embodiment. The point that the duct 58 of the fourth embodiment is
different from that of the first embodiment lays on the fact that
the duct 58 is constituted by two members, heat conductivities of
which are different from each other. In this connection, the
different points between the first and fourth embodiments will be
mainly detailed in the following, while the duplicate descriptions
same as those of the first embodiment will be omitted.
[0064] The duct 58 of the fourth embodiment is constituted by a
first member 581, including the opposing wall surface 58d serving
as a heat receiving surface for receiving the radiation heat
irradiated from the heating roller 52, and a second member 582
including the duct wall 58e that opposes to the opposing wall
surface 58d, both of which are connected with each other as shown
in FIG. 10. In other words, the duct 58 of the fourth embodiment is
constituted by two members including the first member 581 and the
second member 582, which are divided into two members substantially
along the wind blasting direction of the separation wind. In the
abovementioned structure, the first member 581 is made of a
material having high heat conductivity (for instance, an aluminum
or the like), while the second member 582 is made of such another
material that has a heat conductivity being lower than that of the
first member 581 (for instance, a resin material or the like).
[0065] According to the fourth embodiment as described in the
above, the duct 58 is so constituted that the duct wall 58e,
opposing to the opposing wall surface 58d (heat receiving surface),
is made of such the material, the heat conductivity of which is
lower than that of the other material, of which the opposing wall
surface 58d serving as the heat receiving surface is made.
According to the abovementioned structure, it becomes possible to
suppress an occurrence of such an inconvenient situation that the
heat retained within the separation wind is dispersed outside the
duct 58 through the duct wall 58e. As a result, it becomes possible
to suppress the deterioration of the heating efficiency of the
separation wind, and accordingly, it becomes possible to
efficiently heat the separation wind.
[0066] Further, it is needless to say that the fourth embodiment is
combinable with the second embodiment including the plurality of
heat condensing fins 58f and/or the third embodiment including the
plurality of heat radiation fins 58g.
[0067] Although the several examples of the image forming apparatus
embodied in the present invention have been described in the
foregoing, it is needless to say that modifications and additions
made by a skilled person in regard to the exemplified embodiments
without departing from the spirit and scope of the invention shall
be included in the scope of the present invention. Further, the
fixing device itself functions as a part of the present invention.
In this case, it is applicable that the configuration of the fixing
device includes the wind blasting section as its constituent, or
does not include the wind blasting section as its constituent on
the premise that the fixing device is provided with such a
connection structure that suppresses the heat conduction with the
wind blasting section.
[0068] According to the present invention, since the heat
conducting action from the duct to the air blasting section is
suppressed, it becomes possible to prevent the air blasting section
from deterioration caused by heat transferred from the duct.
Accordingly, it becomes possible to stably operate the separating
section, resulting in an extension of its lifetime.
[0069] While the preferred embodiments of the present invention
have been described using specific term, such description is for
illustrative purpose only, and it is to be understood that changes
and variations may be made without departing from the spirit and
scope of the appended claims.
* * * * *